<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <link rel="stylesheet" href="static/plugins/bootstrap-3.4.1/css/bootstrap.css">
    <style>
        .login{
            position: fixed;
            width: 400px;
            height: 300px;
            border: 1px solid #adadad;
            left: 0;
            right: 0;
            top: 0;
            bottom: 0;
            margin: auto;
            padding: 20px 10px;
            box-shadow: 2px 2px 5px #8c8c8c;
        }
        .font{
            text-align: center;
        }
    </style>
</head>
<body>
<div class="login">
    <form>
        <div class="font"><h1>用户登录</h1></div>
        <div class="form-group">
            <label for="exampleInputEmail1">用户名</label>
            <input type="email" class="form-control" id="exampleInputEmail1" placeholder="Username">
        </div>
        <div class="form-group">
            <label for="exampleInputPassword1">密码</label>
            <input type="password" class="form-control" id="exampleInputPassword1" placeholder="Password">
        </div>
        <button type="submit" class="btn btn-success">登录</button>
    </form>
</div>
</body>
</html>